Clustering date ranges without overlapping. (Timeline bar chart)

[emorbidoni]

Hi, I'm stuck with this issue, please help!

I have a variable set of dates ranges, and I need to assign each range a number (or label) and avoid overlapped ranges in the same label.
So the numbers (or labels) will be the "Y-Series" for a timeline bar chart.

I need to get the minimum number of "labels" with no overlapped ragnges (3 in the case behind).

Explample of the set:

start date end date

[TABLE="width: 160"]
<colgroup><col width="80" span="2" style="width:60pt"> </colgroup><tbody>[TR]
[TD="class: xl65, width: 80, align: right"]04/2008[/TD]
[TD="class: xl65, width: 80, align: right"]06/2008[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]04/2008[/TD]
[TD="class: xl65, align: right"]05/2008[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]07/2008[/TD]
[TD="class: xl65, align: right"]08/2018[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]07/2008[/TD]
[TD="class: xl65, align: right"]08/2008[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]09/2008[/TD]
[TD="class: xl65, align: right"]07/2014[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]08/2009[/TD]
[TD="class: xl65, align: right"]08/2009[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]08/2011[/TD]
[TD="class: xl65, align: right"]08/2011[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]12/2013[/TD]
[TD="class: xl65, align: right"]12/2013[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]02/2014[/TD]
[TD="class: xl65, align: right"]07/2014[/TD]
[/TR]
[TR]
[TD="class: xl65, align: right"]09/2014[/TD]
[TD="class: xl65, align: right"]10/2014[/TD]
[/TR]
</tbody>[/TABLE]


I need a formula to get the first column:


[TABLE="width: 240"]
<colgroup><col width="80" span="3" style="width:60pt"> </colgroup><tbody>[TR]
[TD="width: 80, align: right"]1[/TD]
[TD="class: xl65, width: 80, align: right"]04/2008[/TD]
[TD="class: xl65, width: 80, align: right"]06/2008[/TD]
[/TR]
[TR]
[TD="align: right"]2[/TD]
[TD="class: xl65, align: right"]04/2008[/TD]
[TD="class: xl65, align: right"]05/2008[/TD]
[/TR]
[TR]
[TD="align: right"]1[/TD]
[TD="class: xl65, align: right"]07/2008[/TD]
[TD="class: xl65, align: right"]08/2018[/TD]
[/TR]
[TR]
[TD="align: right"]2[/TD]
[TD="class: xl65, align: right"]07/2008[/TD]
[TD="class: xl65, align: right"]08/2008[/TD]
[/TR]
[TR]
[TD="align: right"]2[/TD]
[TD="class: xl65, align: right"]09/2008[/TD]
[TD="class: xl65, align: right"]07/2014[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="class: xl65, align: right"]08/2009[/TD]
[TD="class: xl65, align: right"]08/2009[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="class: xl65, align: right"]08/2011[/TD]
[TD="class: xl65, align: right"]08/2011[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="class: xl65, align: right"]12/2013[/TD]
[TD="class: xl65, align: right"]12/2013[/TD]
[/TR]
[TR]
[TD="align: right"]3[/TD]
[TD="class: xl65, align: right"]02/2014[/TD]
[TD="class: xl65, align: right"]07/2014[/TD]
[/TR]
[TR]
[TD="align: right"]2[/TD]
[TD="class: xl65, align: right"]09/2014[/TD]
[TD="class: xl65, align: right"]10/2014[/TD]
[/TR]
</tbody>[/TABLE]


Thanks!